Exploring the Synergy: Experimental and Theoretical Investigation of Steel and Glass Fiber Reinforced Polymer (GFRP) Reinforced Slab Incorporating Alccofine and M-Sand

Introduction: This study investigates the Experimental and Theoretical Investigation of Steel and Glass Fiber Reinforced Polymer (GFRP) Reinforced Slab Incorporating Alccofine and M-sand. Objective: Specific objectives include evaluating the mechanical properties and structural behaviour of steel and GFRP-reinforced one-way slabs and comparing experimental and theoretical predictions. Methods: Four different mix proportions were arrived at, comprising both conventional concrete and Alccofine-based concrete. In each formulation, a combination of normal river sand and M-sand was utilized. Results: Concrete with Alccofine exhibits superior mechanical properties, while M-sand incorporation minimally affects strength but reduces reliance on natural sand. GFRP-reinforced slabs display distinct brittle behaviour with significant deflections post-cracking, contrasting steel-reinforced slabs’ gradual, ductile failure. Discrepancies between experimental data and design recommendations underscore the need for guideline refinement. Conclusion: Alccofine and M-sand enhance concrete properties, but reinforcement type significantly influences slab behaviour. GFRP-reinforced slabs, though exhibiting lower values than steel, offer advantages in harsh environments, warranting further optimization.

Damage response of conventionally reinforced two-way spanning concrete slab under eccentric impacting drop weight loading

Reinforced concrete(RC)structures are generally designed to carry quasi-static gravity loads through almost indispensable components namely slab,however,it may be subjected to high intense loads induced from the impact of projectiles generated by the tornado,falling construction equipment,and also from accidental explosions during their construction and service lifespan.Impacts due to rock/boulder falls do occur on the structures located especially in hilly areas.Such loadings are not predictable but may cause severe damage to the slab/structure.It stimulates structural engineers and researchers to investigate and understand the dynamic response of RC structures under such impulsive loading.This research work first investigates the performance of 1000×1000×75 mm^(3)conventionally reinforced two-way spanning normal strength concrete slab with only tension reinforcement(0.88%)under the concentric impact load(1035 N)using the finite element method based computer code,ABAQUS/Explicit-v.6.15.The impact load is delivered to the centroid of the slab using a solid-steel cylindroconical impactor(drop weight)with a flat nose of diameter 40 mm,having a total mass of 105 kg released from a fixed height of 2500 mm.Two popular concrete constitutive models in ABAQUS namely;Holmquist-Johnson-Cook(HJC)and Concrete Damage Plasticity(CDP),with strain rate effects as per fib MODEL CODE 2010,are used to model the concrete material behavior to impact loading and to simulate the damage to the slab.The slab response using these two models is analyzed and compared with the impact test results.The strain rate effect on the reinforcing steel bars has been incorporated in the analysis using the Malvar and Crawford(1998)approach.A classical elastoplastic kinematic idealization is considered to model the steel impactor and support system.Results reveal that the HJC model gives a little overestimation of peak displacement,maximum acceleration,and damage of the slab while the predictions given by the CDP model are in reasonable agreement with the experimental test results/observations available in the open literature.Following the validation of the numerical model,analyses have been extended to further investigate the damage response of the slab under eccentric impact loadings.In addition to the concentric location(P1)of the impacting device,five locations on a quarter of the slab i.e.,two along the diagonal(P2&P3),the other two along the mid-span(P4&P5),and the last one(P6)between P3 and P5,covering the entire slab,are considered.Computational results have been discussed and compared,and the evaluation of the most damaging location(s)of the impact is investigated.It has been found that the most critical location of the impact is not the centroid of the slab but the eccentric one with the eccentricity of 1/6th of the span from the centroid along the mid-span section.

Design and Construction Technology of Prefabricated Reinforced Concrete Slab Culverts

Compared with traditional cast-in-situ concrete slab culverts,prefabricated reinforced concrete slab culverts can be produced more quickly and has strong quality controllability,strong earthquake resistance,and repeatability.They will be the primary production method of slab culverts in the future.This article offers a comprehensive review of the design and construction technology associated with prefabricated reinforced concrete slab culverts.The objective is to provide a valuable reference for related enterprises,enhance the quality of design and construction in precast pile configuration,and,in turn,contribute to the advancement of construction projects within our country.

Analysis and Prediction Model Reinforced UHPC Shrinkage Property

This paper explores the shrinkage of reinforced UHPC under high-temperature steam curing and natural curing conditions.The results are compared with the existing shrinkage prediction models.The results show that the maximum shrinkage strain of reinforced UHPC after steam curing is 164μεand gradually becomes zero.As for natural curing,the maximum shrinkage strain is 173μεand the value stabilizes on the 10th day after pouring.This indicated that steam curing can significantly reduce shrinkage time.Compared with the plain UHPC tested in the previous literature,the structural reinforcement can significantly inhibit the UHPC shrinkage and greatly reduce the risk of cracking due to shrinkage.By comparing the results in this paper with the existing models for predicting the shrinkage strain development,it is found that the formula recommended in the French UHPC structural and technical specification is suitable for the shrinkage curve in the present paper.

Mechanical Characterization of Rhecktophyllum Camerunense (RC) Fiber Reinforced Concrete

This work presents the development and mechanical characterization of a concrete reinforced with plant fiber extracted from Rhecktophyllum Camerunense (RC), a plant found in the regions of Center and South Cameroon. A comparative study between ordinary concrete and concrete reinforced with RC fiber at different percentages (0.1%, 0.2% and 0.3%) was carried out. The mechanical characterization of the material consisted in studying the flexural, compressive and splitting tensile strength by using cylindrical specimens of dimensions 160 × 320 in accordance with standards EN 12390-3 and EN 12390-6. The study of the mechanical properties was completed by the three-point bending test using prismatic test specimens of dimension 40 × 40 × 160 made according to the EN 196 standard. It emerges from this work that the addition of RC fiber improves the mechanical properties of concrete up to 0.2% with a peak at 0.1% of fiber corresponding to respective increases of 9%, 16% and 6% of the values of mechanical resistance to compression, flexion and tension after 28 days. From 0.3% of fiber, the values of the mechanical characteristics of the composite drop to values lower than those of ordinary concrete. The density reduction rate at 28 days is about 10% compared to the mass of ordinary concrete. These results allow us to conclude that the RC fiber could be valorized for the production of lightweight concrete.

Mechanical Characterization of Rhecktophyllum Camerunense (RC) Fiber Reinforced Concrete

This work presents the development and mechanical characterization of a concrete reinforced with plant fiber extracted from Rhecktophyllum Camerunense (RC), a plant found in the regions of Center and South Cameroon. A comparative study between ordinary concrete and concrete reinforced with RC fiber at different percentages (0.1%, 0.2% and 0.3%) was carried out. The mechanical characterization of the material consisted in studying the flexural, compressive and splitting tensile strength by using cylindrical specimens of dimensions 160 × 320 in accordance with standards EN 12390-3 and EN 12390-6. The study of the mechanical properties was completed by the three-point bending test using prismatic test specimens of dimension 40 × 40 × 160 made according to the EN 196 standard. It emerges from this work that the addition of RC fiber improves the mechanical properties of concrete up to 0.2% with a peak at 0.1% of fiber corresponding to respective increases of 9%, 16% and 6% of the values of mechanical resistance to compression, flexion and tension after 28 days. From 0.3% of fiber, the values of the mechanical characteristics of the composite drop to values lower than those of ordinary concrete. The density reduction rate at 28 days is about 10% compared to the mass of ordinary concrete. These results allow us to conclude that the RC fiber could be valorized for the production of lightweight concrete.

Pressure-impulse diagram with multiple failure modes of one-way reinforced concrete slab under blast loading using SDOF method

Two loosely coupled single degree of freedom (SDOF) systems were used to model the flexural and direct shear responses of one-way reinforced concrete slabs subjected to explosive loading. Blast test results show that the SDOF systems are accurate in predicting the failure mode of the slab under blast loads by incorporating the effects of the strain rate effect caused by rapid load application. Based on different damage criteria, pressure-impulse (P-I) diagrams of the two failure modes were analyzed with the SDOF systems. The effects of span length, concrete strength, and reinforcement ratio of the slab on the P-I diagram were also investigated. Results indicate that a slab tends to fail in direct shear mode when it is of a smaller span length and tends to fail in flexure mode when it is of a larger span length. With the increase of the concrete strength or reinforced ratio, both the flexure and shear capacity increase. Based on numerical results, a simplified method and a semi analytical equation for deriving the P-I diagram are proposed for different failure modes and damage levels.

Damage analysis of POZD coated square reinforced concrete slab under contact blast

High efficiency, environmental protection and sustainability have become the main theme of the development of the protection engineering, requiring that the components not only meet the basic functions, but also have chemical properties such as acid and alkali corrosion resistance and aging resistance. Polyisocyanate-oxazodone(POZD) polymer has the above characteristics, it also has the advantages of strong toughness, high strength and high elongation. The concrete slab sprayed with POZD material has excellent anti-blast performance. In order to explore the damage characteristics of POZD sprayed concrete slabs under the action of contact explosion thoroughly, the contact explosion test of POZD concrete slabs with different charges were carried out. On the basis of experimental verification,numerical simulation were used to study the influence of the thickness of the POZD on the blast resistance of the concrete slab. According to the test and numerical simulation results that as the thickness of the coating increases, the anti-blast performance of the concrete slab gradually increases,and the TNT equivalent required for critical failure is larger. Based on the above analysis, empirical expressions on normalized crater diameter, the normalized spall diameter and normalized spall diameter are obtained.

Analytical Solutions to Strain Rates of Reinforced Concrete Simply Supported Slabs under Blast Loads

Based on the Duhamel integral, a couple of analytical solutions are derived to predict the strain rates of concrete and steel reinforcement in reinforced concrete slabs under blast loads and to estimate their variation over depth of a cross-section along the entire length of the member. The analytical approach utilizes the single-degree-of-freedom mode for the analysis of reinforced concrete simply supported one-way panels subjected to blast loads. These analytical solutions can give the strain rate profile for any cross-section at any time and permit variations of strain rate in each time step of numerical iteration method, thus making it possible to directly incorporate strain rate effects into non-linear dynamic response analysis of structural members subjected to blast loads.

NONLINEAR ANALYSIS OF REINFORCED CONCRETE RECTANGULAR SLABS USING FINITE ELEMENT METHOD

The nonlinear analysis of reinforced concrete rectangular slabs undermonotonic transverse loads is performed by finite element method.The layered rectangu-lar element with 4 nodes and 20 degrees of freedom is developed,in whichbending-stretching coupling effect is taken into account.An orthotropic equivalentuniaxial stress-strain constitutive model of concrete is used.A program is worked out andused to calculate two reinforced concrete slabs.The results of calculation are in goodconformity with the corresponding test results.In addition,the influence of tension stif-fening effect of cracked concrete on the results of calculation is discussed.

Performance Evaluation of One-Way Concrete Slabs Reinforced with New Developed GFRP Bars

The incorporation of fiber-reinforced-polymer (FRP) bars in construction as a replacement to steel bars provides a superior material which is capable to overcome corrosion problems. However, serviceability requirements are important issues to be considered in the design of concrete elements reinforced with glass-FRP (GFRP) bars which are known to have larger deflections and wider crack widths as well as weaker bond compared with steel reinforced concrete. As a solution to this problem, square GFRP bars are proposed. This paper presents the results of an experimental investigation that was performed, in which newly developed square and circular GFRP bars were fabricated in the lab. Also, the GFRP bars were tested and used to reinforce concrete slabs. A total of nine full-scale GFRP-reinforced concrete (RC) one-way slabs were constructed, tested and analyzed, considering the most influencing parameters such as the cross sectional shape of GFRP bars, reinforcement ratio, the concrete characteristics strength, and adding polypropylene fibers to the concrete mixture. The test results were showed that, the tested slabs with GFRP square bars improved the deflection and cracking behavior as well as the ultimate load.

Effects of edge beams on mechanic behavior under lateral load in reinforced concrete hollow slab-column structure

In order to get the formulae for calculating the equivalent frame width coefficient of reinforced concrete hollow slab-column structures with edge beam,the finite element structural program was used in the elastic analysis of reinforced concrete hollow slab-column structure with different dimensions to study internal relationship between effective beam width and the frame dimensions.In addition,the formulas for calculating the increasing coefficient of edge beam were also obtained.

Structural Glass Fiber Reinforced Concrete for Slabs on Ground

This paper aims to contribute to the classification and specification of glass fiber reinforced concrete (GFRC) and to deal with the question if structural glass fiber reinforced concrete as a special kind of glass fiber reinforced concrete is suited for use in load-bearing members. Despite excellent material properties, the use of glass fibers in a concrete matrix is carried out so far only in non- structural elements or as a modification for the prevention of shrinkage cracks. The aim of re- search at the University of Applied Sciences in Leipzig is the use of alkali-resistant macro glass fibers as concrete reinforcement in structural elements as an alternative to steel fiber reinforcement. Slabs on ground, as an example for structural members, provide a sensible application for the new material because they can be casted as load bearing and non-load bearing and are mostly made of steel fiber reinforced concrete. In the future, structural glass fiber reinforced concrete shall provide a simple and visually appealing alternative to conventional steel bar or steel fiber reinforced concrete. The glass fibers can also be used in combination with conventional reinforcing bars or mat reinforcements. Initial investigations have announced some potential.

纤维织物增强高延性混凝土加固RC短柱抗剪性能试验研究

为研究纤维织物增强高延性混凝土(TR-HDC)加固钢筋混凝土短柱的抗剪性能,设计了6根钢筋混凝土柱,包括2个对比柱和4个TR-HDC加固柱.通过低周反复荷载试验,对比分析剪跨比、纤维织物层数对试件破坏形态、变形、承载力和耗能能力的影响.结果表明:采用TR-HDC加固钢筋混凝土短柱,可显著提高其抗剪承载力;TR-HDC与原混凝土柱协同工作性能良好,加固后的混凝土柱的变形、承载力和耗能能力明显提高;增加纤维织物的层数对钢筋混凝土短柱的抗剪承载力提高幅度较小,但可大幅增强柱的耗能和变形能力;剪跨比较大时,更有利于发挥TR-HDC加固材料的力学性能.基于桁架-拱模型,提出TR-HDC加固钢筋混凝土短柱的抗剪承载力计算方法,计算结果较准确.

附设黏滞阻尼器的RC框架结构抗震韧性评估

为研究黏滞阻尼器对钢筋混凝土(reinforced concrete,RC)框架结构抗震韧性影响,基于增量动力时程分析方法,对附设黏滞阻尼器的RC框架结构开展抗震韧性能力评估。结合FEMA P-58以及我国抗震韧性评价标准,将主要受损构件的修复费用、修复时间曲线以及易损性信息按实际情况进行相应修正,并对无控结构和有控结构的修复费用、修复时间和人员伤亡等主要抗震韧性指标进行对比分析,明确了黏滞阻尼器对RC框架结构抗震韧性的影响。研究表明,在RC框架结构中适当设置黏滞阻尼器不仅能够减小结构地震响应、降低结构破坏概率,还能有效提升结构抗震韧性。

RC框架梁端负弯矩纵筋部分置于梁侧楼板对性能的影响及构造问题分析

为适应建筑多功能、大跨度、重荷载、高抗震的发展要求,框架梁端部负弯矩纵筋配筋率通常较高,节点区钢筋过于密集,混凝土施工质量不易保证,对结构综合性能有不利影响。先对梁端负弯矩纵筋部分设置于梁侧楼板内(简称APNRFS)的布筋方式进行阐述,然后基于试验结果分析探讨了该配筋方式对结构性能带来的变化及相关构造问题。研究表明:梁端采用APNRFS布筋方式一般不会降低框架梁的承载力;梁端的弯曲变形能力和结构抗震性能有一定提高;移至板内的梁负筋布置宽度宜小于有效翼缘宽度范围;移至板内的梁端负筋宜同时兼作楼板负筋;横向分布筋参与受力,设计中应适当增配。

功能可恢复RCS混合框架结构研究进展

钢筋混凝土柱-钢梁(RCS)混合框架结构以其结合了混凝土优异的抗压性能及钢材优异的抗弯性能而受到广泛关注,而可恢复功能结构以其震后快速恢复使用功能的能力,也成为地震工程界研究的新热点。功能可恢复RCS混合框架结构可以在弯矩较大的梁端和柱脚部位设置可更换构件,实现结构的功能可恢复能力。文中简述了近年来功能可恢复RCS混合框架结构研究进展,重点关注各类型功能可恢复钢梁、功能可恢复摇摆柱脚的构造研究,介绍了功能可恢复RCS混合框架结构性能分析研究进展。最后,对功能可恢复RCS混合框架结构仍需深入研究的问题进行了展望。

UHPC-RC节段组合梁的抗弯性能分析

为研究低预应力度条件下,不同节段接缝的超高性能混凝土-钢筋混凝土(ultra-high performance concrete-reinforced concrete,UHPC-RC)组合梁的抗弯性能,文章基于ABAQUS有限元软件,建立UHPC-RC节段组合梁的基准有限元模型,并利用已有的试验数据验证该模型的合理性。节段接缝分别为平面干接缝、平面胶接缝、齿键干接缝和齿键胶接缝,在基准有限元模型的基础上,进一步研究节段接缝类型对组合梁抗弯性能的影响。研究发现,在四点受弯加载方式下,接缝的几何特征(平面或齿键)对组合梁的极限荷载和开裂荷载影响较小,环氧树脂胶的使用对组合梁的抗弯性能影响较大。

BFRP模壳不排水加固RC墩柱恢复力模型

为研究玄武岩纤维增强聚合物(basalt fiber reinforced polymer, BFRP)模壳不排水加固钢筋混凝土(reinforced concrete, RC)墩柱抗震恢复力模型,在拟静力试验基础上,采用OpenSees有限元软件对模壳加固墩柱进行数值分析,主要研究参数为填充层混凝土强度、模壳厚度、加固高度、轴压比。研究表明:填充层混凝土强度等级越高,墩柱抗震性能有所增强,但C40以上的填充层混凝土强度等级墩柱的抗震性能较为接近;模壳加固厚度较大墩柱的抗震性能优于厚度较小墩柱;当模壳加固高度较高时,墩柱的抗震性能较好,当加固高度大于2~3倍原墩柱塑性铰高度时,抗震性能提升效果趋于稳定;轴压比越大,墩柱的刚度退化较快,不利延性发展。后通过数据回归分析,建立了BFRP模壳加固RC墩柱恢复力模型,对比可知,恢复力模型与试验曲线拟合较好,能有效反映加固墩柱的滞回性能,可为此类结构的抗震性能分析提供参考。

Dynamic responses of reinforced concrete beams under double-endinitiated close-in explosion

The reinforced concrete(RC) structural component might suffer a great damage under close-in explosion.Different from distant explosions, blast loads generated by the close-in explosion are non-uniformly distributed on the structural component and may cause both local and structural failure. In this study,an experimental study was conducted to investigate the dynamic responses of RC beams under doubleend-initiated close-in explosions. The experimental results show that the distribution of blast loads generated by the double-end-initiated explosion is much more non-uniform than those generated by single-point detonation, which is caused by the self-Mach-reflection effects. A 3 D finite element model was developed and validated in LS-DYNA by employing the modified K&C model. Intensive numerical calculations were conducted to study the influences of the initiation way, scaled distance and longitudinal reinforcement ratio on the dynamic responses and failure modes of RC beams. Numerical results show that the RC beam suffers greater damage as the cylindrical explosive is detonated at its double ends than the scenario in which the cylindrical explosive is detonated at its central point. RC beams mainly suffer flexural failure and flexure-shear failure under the double-end close-in explosion, and the failure modes of RC beams change from the flexural damage to flexure-shear damage as the scaled distance or the longitudinal reinforcement ratio decreases. The direct shear failure mode is not usually observed in the double-end-initiated explosion, since the intense blast loads is basically concentrated in the midspan of RC beam, which is due to self-Mach-reflection enhancement.